Impact hammer



Feb.r24, 1959 c. E. sENNHoLTZ ETAL 2,874,912

IMPACT HAMMER Filedl March 14, 195'/ 2 sheets-sheet 1 Feb.2`4, l959-l c;E. SENNHOLTZ ETAL 2,874,912

Y IMACT HAMMER Filed March 14, 1957 2 sheds-sheet 2 time@ Sees IMPACTHAMMER Charles EVSennholtz and Thomas E. Bridgewater,

` Chicago, Ill.

Application March 14, 1951, `serial No. 646,665 4 Claims. (ci. :4l-i197)This invention relates generally to crushing and pulverizing hammermills, andmore particularly to a two-piece rotary impacthammerlfor usein suchV devices;

In hammer mills designed for rotary crushing it is well known tomountr'emovable impact hammers on rotatable drums so that the hammersmaybe replaced when worn `from service use. However, these hammers arecommonly "formed ofmanganese steel andare quite heavy, an average hammerweighing approximately 400 lbs. Therefore, va considerable amount ofmetal must `be used earch time the head of the hammer becomes too wornfor further use. Moreoventhe weight not only makes replacement ldifcultin the actualphysical handling of the hammer,

but also contributes toproducing a considerable centrifugal force duringoperationwhich requires heavy duty `fastenings tosecurethe hammer to itsdrum. The need cal toJ operate,` and yet is formed so as to be easilyand inexpensively manufactured.

1t is "anotherlbjct tolprovide a two-piece impact hammerfofthe""ty`p`ereferredtoabove whose parts are notupset or jammed intoengagement bythe normal work- "ing impacttorces to` which it"`issubjected so' that replace* ment of the removablefportion may be readilyaccomu l"plished even"af`ter""long .periods of use. 1

d It isf a furtherob'jebt "to" provide a two-piece hammer oftheaboyecharacter which is locked into operating po sition withnolpossibilityofrelative movement or play'by `a singlejeasilyreplaceable`fastener.`

"Other objects "and advantages of the invention will become` apparentuponi reading the attached detailed .de-

"'scriptionanjd upon reference tofthe drawingsin which:

.Figure 1 showsanexploded perspective view of a two piece impact hammerconstructed according tothe present invention g `Fig; 2is apartialendview of the hammer shown in Fig. lm when assembled.

Fig. 3 is"a"fragmentarysectionalview taken along the line`3--3 ofFigfZ.` l

Fig. 4 is afragmentary sectional view of the impact hammer of Fig. lassembled and mounted atthe periphery of a rotatable drum. d d

Fig.f5is-afragmentarysectional view taken along the 'line 5 5 ofl Fig.`2.

Fig. 6 is a transverse sectional view taken along line 646 of Fg.5.

Fig. 7 is `a frgamentary bottom view of the replace- -able hammer-headshown in Figpl,

structed according to the` present invention `shown "in partial section.

Fig. 9 is a side view ofthe hammer base designed to cooperate with thehead shown in Fig. `8.

Fig. 10 is a transverse sectional view taken along line 1liitl of Fig.9.

Fig. 11 is a fragmentary plan view of the hammerfbas'e shown in Fig. 9.d Fig. l2 is an end view ofthe hammer headishown'in Fig. 8.

Fig. 13 is an end view of the hammer base and head shown in Fig. 9 inassembled relation. d

Fig. 14 is a perspective view of` a lockingplugiu'sedto secure thehammer `shown in Fig. 13. Y

While the invention will be described in connection with certainpreferred embodiments,=it will be understood that l do not intend tolimit the invention to such embodiments but, on the contrary, intend tocover 4such alternative embodiments and constructionsas may be includedwithin the spirit and scope of t'he appended claims.

Turning iirst to Fig. 1, there is shown a two-piece impact hammer 10constructed according to the present invention and consisting of ashankor body portion `11 and a hammer head 12, which is firmly but removablysecured onto the shank. in a conventional hammer millaplurality of `suchhammers are mounted at the periphery of a rotatable drum 13, a portionof which is shown in'Fig. `4. For attaching the body of the hammer 10 toa drum, the

shank is formed having two longitudinally `extending grooves le and l5,one on each side, which denes an enlarged foot portion .le that isreceived Within an undercut groove i7 in the drum 1?. The hammer shank11 is rmly secured within the groove 17` by forming one of the latterswalls as a key portion 13 shaped to t within the groove 14 and byproviding a removable wedge 19 of similar shape to engage andt withinthegroove 17. The assembly is locked in place by tightening a bolt 21,which is threaded through a hole 2 in drum 13, against `wedge 19 andthus holding the wedge 19, shank -11 and drum 13 rigidly together.

ln accordance with the present invention, the upper rsurface of theshank 11 has a seating surface from which `projects a series ofoverhanging wedges, and the lower surface of hammer head 12 has'acomplementary seating surface with a series of wedge-receivingopeningsand a `complementary series of Wedges arranged so that the twoseries of wedges inter-engage upon relative edgewise lmovement oftheshank and head with the seating sur- "faces in Contact, and, thus,firmly lock theheadonto the shank. in the present embodiment, theseating surface 24 on the shank l1 is at and the overhanging series ofWedges 25 extend laterally from a central opstanding ridge 26. Forreceiving the ridge 26 and the seriesof wedges `12.5, the head 12 has agroove 27 surrounded by a flat `seating surfaced which matches thesurface 24 on shank lll. Arranged on each of the side walls of thegroove 27 `'are a series ofcomplernentary wedges 30, spaced from oneanother (see Fig. 7) to allow the ridge 26 and the wedges 25 to passtherebetween.

When the head 12 and shank 11 are to be brought into association, thegroove 27 in head 12 is alined with the ridge 26 and the head is loweredso that the wedges 30 are moved on either side of the ridge and betweenthe wedges 25. When the seating `surface 28 rests on the surface 24, thehead 12 may be movedlengthwise of the shank to carry the wedges 30beneath the complementary wedges 25 and thus lock the head and shanktogether.

It is a feature of the invention that the head and shank of the hammer10 are locked together without looseness'or play by providing the wedges25 and 30 with complementary tapering surfaces. In the disclosedembodiment eachwedge 25 has two tapering surfaces 31, 32 and' overlies athird wedge-shaped portion 33 formed integrally with ridge 26 (see Fig.1). Cooperating with these tapered surfaces are'the surfaces 34, 35 onwedges 30 and wedge portions 36 formed on the sides of groove 27 (seeFig. 6), so that when the shank and head are relatively shifted to lockthe wedge 30 beneath the complementary wedges 25, the surfaces 31 and36, 32 and 35, and 33 and 34 will sliderinto tight wedging engagementagainst one another and the head 12 will lbe firmly locked on the shank11.

In carrying out the invention, means are provided to secure the head 30against sliding movement when the head and shank are locked together sothat these parts cannot be separated accidentally. In the firstembodiment disclosed, this securing means takes the form of a bolt 40which may be passed through a ange 41 formed on the head 12 and threadedinto a nut which is positioned and secured within the recess 43 formedin the top, and at one end, of the ridge 26. A hole 44 provides accessto the recess 43 for the bolt 40. Flange 41 is spaced inwardly from theend of head 12 and the head 11 so that the head of bolt 40 is protectedby the surrounding portions of the hammer unit 10 from direct contactwith the material being crushed or pulverized. In the present instance,the nut 42 is secured in proper position within the recess 43 by beingbrazed into place.

To ensure that the head 12 may be slid far enough along surface 24 to besecurely wedged into place, the ange 41 and the end of ridge 26 at whichrecess 43 is located are proportioned so that when they are drawn intoabutment -by tightening bolt 40 the head 12 is tightly wedged intoproper position on the shank 11. Pursuant to the invention, analternative form of securing means is shown in Figs. 8 to 13. In thisembodiment elements similar to those referred to above in connectionwith the first modification have been given the same numericaldesignations with the suflix a added.

In order to secure the head 11a and shank 12a against relative slidingmovement a projecting leg 50 is extended downwardly from the head 12a tobe received in a rectangular recess 51 that extends through the ridge26a and into the center of the shank 11a. It can be noted that therecess 51 is substantially longer than the width of leg 50, so'that theleg may be received and longitudinally moved therein when the head 12ais lowered onto the surface 24a and the wedges 25a are passed between,and slid beneath the wedges 30a.

When the head 12a is slid along surface 24a, to the left in Fig. 9, andis locked in full wedging engagement onto the shank 11a, it can be seenthat the depending leg 50 will be disposed at the left of the recess 51.To restrain the head 12a against sliding movement in the oppositedirection, which would release the head from the shank 11a, a yblockingplug 55 is disposed in the path of leg 50 by inserting the plug in atapered hole 56 formed through the shank 11a. When tightly wedged intoposition, the tapered plug 55 snugly engages a notch 57 formed in leg 50and holds the head 12a tightly wedged onto the shank 11a. So that theplug 55 may be properly positioned, it is formed with a circular flange57 at its wider end, which engages and fits within a recess 58 on theside wall of shank 11a. Thus, the plug 55 can be properly positioned bydriving it home until further movement is prevented by flange 57 beingseated within the recess 58. To remove the plug, it is only necessary tostrike it from the opposite side of the opening 56 and force itoutwardly. When the plug 57 is in its fully inserted position, it can beseen that the hammer 10a can be placed within groove 17 in the rotarydrum 15 and the key portion 18 and wedge 19 can snugly engage the shank11a and thus prevent the plug from being accidentally dislodged as anincident to holding the hammer 10a onto the drum 15.

It will be appreciated that hammers of this type are subjectto violentshock loads during the normal course tion ofthe impact forces, andtransverse to the centrifugal force which tends to throw the hammer headoutwardly from the rotating drum. Moreover, it will be appreciated thatthe securing means shown in each of the disclosed embodiments are notcalled upon to resist the forces imposed on the hammer as an incident tonormal operation. And thus these securing means need be only of lightduty, easy to manipulate, types which make removal and replacement of ahammer head simple and convenient.

Furthermore, it can be seen that the disclosed hammer head and shank canbe conveniently cast as single structural units, which both increasestheir strength and durability and decreases their cost of manufacture.

While, in the two preferred embodiments shown, each of the complementarywedges 25, 30 and 25a, 30a are formed with matching tapered surfaces sothat each is truly wedge-shaped, it will be apparent that only one setof tapered wedges may be utilized with a complementary set ofnon-tapered wedge blocks without departing from the inventive concept.This is because a wedging action can be obtained when only one of tworelatively sliding surfaces is tapered as well as when both suchsurfaces are tapered.

We claim as our invention:

1. A two-piece impact hammer adapted for luse in a rotary hammer millcomprising, in combination, an elongated shank having an upper seatingsurface and a longitudinally extending ridge projecting from saidsurface, a hammer head having a lower seating surface in smooth, uniformengagement with said upper seating surface and havinga groove to receivesaid ridge, two complementary series of locking members, one seriesprojecting laterally from said ridge to overhang said surface and theother series projecting inwardly from the sides of said groove to snuglyunderlie corresponding members of said rst series, said locking membersof each series being spaced so that the members of one series can passbetween the members of the other for permitting said head to be removedfrom said shank, the mutually engaging surfaces of said locking membersbeing oppositely tapered so as to exert a wedging force holding saidhead against said seating surface, and the inner edges of the lockingmembers projecting inwardly from the sides of said groove and the sideportions of the ridge which said inner edges engage also beingoppositely tapered so as to wedge said head into fixed longitudinalalinement on said shank.

2. A two-piece hammer adapted to be mounted on a rotatable drumcomprising, in combination, an elongated hammer body having alongitudinal upstanding ridge on its upper surface, an elongated hammerhead having a longitudinal groove on its lower surface adapted toreceive said upstanding ridge, a first group of spaced wedges projectingfrom the sides of said ridge, a second group of spaced wedges projectinginwardly from the sides of said groove, the wedges of each group beingoppositely pointed and vertically spaced so that the second group ofwedges on the head can be slid under the,

first group of wedges on the body so as to wedgingly lock the head ontothe body, and releasable means to restrain the head from sliding on saidbody when the head and body are locked together.

3. A two-piece impact hammer adapted to be mounted on a rotatable drumcomprising, in combination, an elongated hammer body having alongitudinal upstanding ridge on its upper surface, an elongated hammerhead having a longitudinal groove on its lower surface adapted toreceive said upstanding ridge, a first group of spaced wedges projectingfrom the sides of said ridge, a second group of spaced wedges projectinginwardly from the sides of said groove, the wedges of each group beingoppositely pointed and vertically spaced so that the second group ofwedges on the head can be slid under the rst group of wedges on the bodyso as to wedgingly lock the head onto the body, a ilange extendingacross said groove and spaced from one end so as to define an outwardlyfacing recess, and means permitting a bolt to be extended through saidflange into threaded engagement with said body to restrain the head fromsliding on the body when they are wedgingly locked together, the head ofsaid bolt being shielded in said recess from accidental damage.

4. A two-piece impact hammer adapted to be mounted on a rotatable drumcomprising, in combination, an elongated hammer body having alongitudinal upstanding ridge on its upper surface, an elongated hammerhead having a longitudinal groove on its lower surface adapted toreceive said upstanding ridge, a first group of spaced wedges projectingfrom the sides of said ridge, a second group of spaced Wedges projectinginwardly from the sides of said grooove, the Wedges of each group beingoppositely pointed and vertically spaced so that the second group ofWedges on the head can be slid under the first group of wedges on thebody so as to wedgingly lock the head onto the body, said body defining.a longitudinally extending groove, a depending leg carried by said headto slide within said last named groove when the groups of wedges areinter-engaged, and a tapered plug inserted through a hole in said bodyso as to Wedge said leg longitudinally in said groove and thuspositively urge and retain said head in locked engagement on said body.

i References Cited in the le of this patent UNITED STATES PATENTS1,305,311 Sheldon et al. v June 3, 1919 2,065,471 Krider Dec. 22, 19362,568,077 Loufek Sept. 18, 1951 2,588,434 Unti et al Mar. 11, 19522,620,989 Keiper Dec. 9, 1952

